Instrument for testing batteries.



C.- J. DAVIDSON.

INSTRUMENT FOR TESTING BATTERIES.

APPLmATIoN FILED 1350.14. 1909.

LQQQQL Patented Mar. i9, 1912 SHEETS-SHEET L A e f5" zfflf/fwfw. Mgmf C. J'. DAVIBSN.

msTRUMENT ma Tamm@ BATTERIES.

APFMGATION FILED DEC. 1.4. $09, L

"awnted i9, 19%? y vUiviinio; sTATEs PATENT' onirica.

CHARLES J'. DAVIDSON, or HACKENS'ACK,

NEW JERSEY, AssrGNon To AMERICAN TELEPHONE AND TELEGRAPH CMPANY,'A CORPORATION OF NEW-YORK.

INS'JIRUIMJEN'J?V FOR .TESTING BATTERIES. 2

sSp1.;c'itcatioxi of Letters Patent'. Patented D131', 19,

Application led December 14, 1909: Serial No. 533,057.

To all inkom imag concern:

Beit known that I, CHARLES J. DAvrDsoN,

` residing at Hackensack, in the county of Bergen and State of New Jersey, have invented certain Improvements in'Instruments for Testing Batteries, of which the following is a` specification.

It is often important in the use of batteries that their efficiency shall not fall much below l`a certain minimum before -they are withdrawn from service. This is especially true of primary batteries employed at telephone substations toV furnish talking current. The current iiow from such batteries through the definite or .known resistance ofjth'e trans`A lnittei' for the average time of a telephonie conversation must be sufficiently great .to

provide for good transmissionylt is therelike elements througliontQFigure 1 is a front elevation of one embodiment of the invention: Fig. 2 is a vertical section'therethrough on the line 2-2 of Fig. 1; Fig. 3 is a rear elevation with the' cover removed and one 1 of a pair of connecting cords shownattached to its terminal; and Fig. 4 is a diagrammatic representation of the 4,circuit arrangement when the instrument is 'in use. i To seeurethe greatest` portability, the operating vparts of my improvedl gage are inclosed in a casing of the watch-case-type', and therefore adapted to be carried in the. pocket, said casing having a' body 10pro- 'vided at its front with a face plate 1 1' over which is a crystal 12 held in the usual bezel 13.v Over. .thev opening in theback 'of the easingl-is a removable cover 14. f

Mounted upon the inner side ofthe face plate, which in the present instance serves as one ,of its heads, is, af s ool 15 having a rear head 16, between' which and the face plate about the cylindrical core is a winding. 17 disposed in sections or coils, whichzsingly or in combination give resistances' proportionate to the apparatus in circuit withfthe battery to betested. For the use of tele'- Aphone inspectors, for which this' instrument y is particularly designed, it isshown as havi ing two coils; the inner. coil 18 mayhave' a resistance. of approximately tive ohms, or substantially that of a low resistance transmittel", and consist of about two hundred and seven turns of #32 enamel covered -copper wire, whilethe 'outer coil 19 may be about fifteen ohms, approximating .when in series with the coil 18a high resistance transmitter,

and have four hundred thirty-tive turns of similar wire.- The coils are insulated from one another and from the spool by paratiin Apaper or other suitable material indicated' at 19a.. I.

Carried byl the face plate adjacent to theA spoolare three terminal plates 20` 21 and 22, l

insulated Ifrom the face plate and from each other by strips-23 of fiber-or .the like'. Screws 24, 24 extend through alined openings in the terminal plates andinsulating strips and are threaded intothe face plates, serving to secure the terminals in place-and' also to electrically connect the outer terminal plate S20 with the'casing. Insulating bushings 25 surround the screws to..prevent contact of the plates 21' and22 therewith.

l The plates Q0 land 21 have lugs 26 to which the outer ends ofthe high and low resistancer coils 19 and`18 are respectively soldered; They also provide terminals for an external circuit, having lateral extensions 27 in which aie,threadcd openings engaged by clamping screws 2S. Under these screws, and projecting between pairs of lugs 29, 29 to prevent turning aboutthe screws, may be securedl suitable terminal tips 30 upon insulated flexible conductors 31, passing from the cas'- ing through openings about-'which44 are to and uponiopposite sides of the usual watch-case 'pendant '33. Upon the outer ends' of the conductors 31 are spring clips 34 by 'which the gage may be attached to the bat# terv to be tested. The third terminal plate 2Q has an inner lug 35 to which the Ajuncture o'fthe high and low resistance coils .are sol-2 dered, and an outer lug-36 projecting beneatlithe stem of the pendant, which has an extension 37 :tor cooperation with .this

lug, the*v Contactin surfaces 38 being of some such metal` as p atinum. Normally these ser? rounded protecting bushings 3Q. -These openings are conveniently located ad]acent` 'surfaces'are held apart by a spring 39 sur'- rounding the stem,'but when the pendant is pressed inwardly these elements serre as a sw'tchf and since the-pendant, asis customary, is iiimetallic contact with the casing,

and since/the terminal plate -2Q is similarly joined lthereto by the screws 24, the higli resistan'ce winding 19 is short circuited, as

-maybefunderstood by referencev to- Fig. 4,

where the line la indicates theentireeelectri- -cal connection between lthe terminal-2O and i the pendant.'

` .The tubular center of the spooljliidopens* through the plate 11 and thereis a similar opening in the rearhead. 'Fixed to the. i plate by screws 3Sb and surrounding the spool openingis an annular plate 38 having an ai'in 39 extending over the center of tlie spoohA and across the opening in the head 1G is a bar 40.- In the arm b9, 4at the axis of the spool, is a depression to receive the end of a pivot or shaft -l-l, the'opposite4 extremity ofwhich is seated in ,a similardepression in the end of a' screw 42'threaded through the har 40. 'Atiaehed to the pivot withii'iy the spool is a vane or armature 43 of soft iron, which, when rcurrent traverses the coils. is repelled b v a sott iron pole-' pieceA4-held within the spool b v a curved stripe-i of non-magnetic metal frictionally extremity ofthe platelea'rries a 46, which non nallwhemthe armature is iivot outside the l face in pi'oxiinityrto the'fole-piecefis maintained a'gainst\aci shionedst'op;dltrising from the .iifted between' the hand 'and thearn'i 3f) with its innei end attached to thepirot and its opposite end fixed to a; post 4f). 'Ihe post passes/through a curved slot. in the plate 38, and has an angulnirend' 5l extending be- .55. lgraduatioridw, y, lindicating cutfol" or re- ]ectionpointsfor batteries associated with ncatli the plate and ela'i'nped in place be- -tween it and. the tace plate h v the screws 3 8; these screws being'loosened, the position of the. post in the slotinav .be varied through the winding, the hand is' actuated by the repulsion between the pole-piece and" armature and is carried toward a stop 52 'simila r to the stop 47. Tn its movement the hand .is carried over a scale printed upon a 1 name to this specification in the presence of .two subscribing witnesses, this ninth` day of face or dial5 2u secured to the plate 1l, this scale'being here illustrated as having two high and low resistance apparatus, resneetively.

Considering now the use of the gagelby telephone inspectors, it may be said that the d or indicating member.;

' Witnesses:

1spring clips ofthe fiexible cords are attached to the terminals of the .battery VB to 4'be' tested, and then, if said battery is in usel with a transmitter of highresistanei` the pendant will be allowed to remain in its -raised position and the two coils are eginected in series giving aresistance betw ,n' the terminals 20 and 21 'of` twenty ohms; or, if the battery is connected with alow resistance transmitter. the pendant will lhc depressed and the high resistance coil short circuited through the switch meinbers'and casing, the. resistance .across the terminals then being tive ohms. Consequently, in each instance. tliere`will be secured the saine cui it "weuldbe subjected in actual service. i

suitable interval for the test` is' one minute,

this being chosen insteadof three minutes, the estimated average length of a telephonie -conversation,- to save' the inspectors time.

the gage beingcalibrated accordingl f. lt the test is for ahigh resistance transmitter battery, and' the. h and isdeflected toward the stop l.Gflsb'eyond `the pointm'and it infallvSting backf'imder'thebintiueiiee .of the dauinlishedvc'urrent How and decreased. repulsion between the oleieee and armature, it does tl e battery 'isfst-ill'in eonditionffor service. l ,uon theA contrary the hand" does n'ot reach the point -mupon the initial closure of' the circuit or at-theend oi the minute is re, traeted,b \`f the`- hair spi-ingle a point be- -iydnil toward..the stop 47. it is air indicaftion5thatfthehnttery.has reached or fallen ence to the point ji/ instead 'of Having .thus described in v invention,` l

claim;

' An instrument teh testing batteries which 'are 1n use with dpparatus having a definite ,resistanetg compiismg a easing. an indicatingv member movablv inounted therein` and an 'actuating coll' the resistance of which renders the resistance ttheinstruinent substantially'equal that o athe apparatus associated with the batteriesto vbe tested,

In testimony whereof, T have signed my December, 1909.'

' CHARLES J. i'iAi'finsoii.y

ALLAN GRAHAM, R. S. Sumar. 

